Lymphocytes in rheumatoid and nonrheumatoid synovial fluids. Nonspecificity of high T-cell and low B-cell percentages.

Lymphocytes were studied in paired peripheral blood and synovial fluid samples from patients with various forms of arthritis, including rheumatoid arthritis (group I) and other polyarthritides of unknown origin (group II), as well as arthritides generally considered not to be immunologically mediated, such as crystal synovitis, traumatic arthritis, osteoarthrosis, and pigmented villonodular synovitis (group III). In all 3 groups the percentages of T lymphocytes were significantly higher in synovial fluids than in the peripheral blood, whereas those of the synovial fluid B lymphocytes were consistently very low and occasionally nil. Absolute numbers of synovial fluid lymphocytes were significantly higher in groups I and II as compared with group III, and in the peripheral blood absolute numbers of lymphocytes in groups I and II were significantly lower than in controls. No correlation was found between absolute numbers of lymphocytes and complement activity in the synovial fluid. The characteristic pattern of high T-cell and very low B-cell percentages in synovial fluids is a general feature of inflammatory exudates and cannot be considered an expression of cell-mediated immunity in itself.